Lookup vs Applymap

[Tanish]

Hello,

Can anyone explain why Applymap function is faster than Lookup function ?

[_Iswarya_]

Hi @Tanish ,

ApplyMap() is more practical since:

• even though you have to load the table, it will be dropped automatically.
•  it makes code easier to understand
• Executed on the distinct values only, not per table record.

Pls find the link below:

https://support.qlik.com/articles/000042949

[marcus_sommer · Accepted solution]

Lookup() has more parameter as applymap() and could look into each table including the currently loaded one. The description within the provided link just explained the performance-impact but not really the cause.

I don't know how it's technically implemented but I wouldn't be surprised as if an applymap() worked like an exists() against the symbol-tables and doesn't break the load-execution while lookup() is applied against the data-tables and may be evaluated separately for each single record.

Beside this is the usage-hint within the description not the whole truth because applymap() could be used with combined and/or sorted fields and also horizontally + vertically nested with a bit advanced scripting. Therefore, there won't be much scenarios in which joins or lookup() are necessary or having a benefit against a mapping.

- Marcus